GROWTH, FEED CONVERSION AND PROTEIN-UTILIZATION OF FLORIDA RED TILAPIA FED ISOCALORIC DIETS WITH DIFFERENT PROTEIN-LEVELS IN SEAWATER POOLS

Twelve outdoor pools (10 m3) receiving flow-through seawater (37 ppt) were stocked with sexreversed male Florida red tilapia fingerlings (10.6 g mean wt.) at a density of 25 fish/m3. Three isocaloric diets containing 20%, 25% and 30% protein of equal quality were tested for effects on fish growth, feed and protein utilization, and carcass composition during growout through full marketable size. Growth rate was high for all diets, with mean weight ranging from 440 to 464 g after 120 days, and survival ranging from 97.0 to 97.5%. There were no significant differences among diets in survival, specific growth rate, daily weight gain, feed consumption and conversion, carcass composition, and fish condition. However, protein efficiency ratio was significantly higher for the 20% protein diet than for diets with higher protein levels. The results demonstrate that Florida red tilapia can be reared in seawater from fingerling through marketable sizes more economically on a 20% protein diet than on diets containing higher protein levels. © 1990.